Robert Stern's book offers a fascinating history of the development of ethics from Kant to Kierkegaard. According to Stern, things end in deadlock—where ‘all that is achieved is a kind of equipollence, making it hard to choose between the theories in a definite manner, where none can claim to have resolved the problem of moral obligation without a significant cost’ (p. 221). Stern's excellent book says something genuinely novel about the history of ethics, and it illuminates a core phenomenon of morality by demonstrating just how difficult it is to explain the nature of moral obligation. Some will probably find its sceptical conclusions frustrating, but I found them refreshing and honest.

The first part of the book is devoted to Kant. According to what Stern calls ‘the standard story’, the development of ethics in this period begins with Kant's invention of the idea of moral autonomy. Kant introduces this idea in order to secure a place for moral objectivity in a universe without values. The self-legislating subject answers to nothing outside itself. Instead, it answers to a procedure of rational choice that confers value on whatever objects or states of affairs are chosen in accordance with this procedure. Stern argues that the standard story is wrong. Kant's discussions of the good will, the formula of humanity, and the value of moral agency all suggest that he is in fact a moral realist of some sort (pp. 26–40). And there is no compelling evidence that he thinks such realism threatens autonomy. His concern is with ‘the problem of obligation’––which is to distinguish between obligation and mere coercion without draining the former of its genuinely binding force. Kant's attempt to solve this problem, rather than his alleged constructivism, is what sets the stage for the Hegelian and Kierkegaardian responses.

According to the standard story, Hegel's central concern is ‘to make sense of a legislative will that relies on no prior order of values, without rendering that willing empty from a normative point of view’ (p. 103). The standard story says that Hegel solves the emptiness problem by situating the individual agent within a historically generated web of norms, practices, and institutions. In the second part of the book, Stern contests this story. He agrees that Hegel socializes the traditionally individualistic concepts of moral philosophy. But he argues that Hegel's turn to the social is not a response to the paradox of self-legislation and anti-realism about value. Rather, it is motivated by his desire (inherited from Schiller) to overcome the ‘dualism’ between reason and inclination built into Kant's solution to the problem of moral obligation. We see this in Hegel's early work, which privileges virtue over duty, ancient ethics over modern morality, and love over law. We also see it in Hegel's mature philosophy, where he offers a ‘social command’ theory of moral obligation. This theory says that moral obligation has its source in the practices and institutions of the modern state. In a way, Hegel's social command account ‘overcomes’ the problem of moral obligation more than it solves it (p. 143). One part of the original problem was to explain how obligation could exert a genuine check on the will. Hegel's view is that the commands of the rational state are commands with which the properly formed individual identifies wholeheartedly. They are not experienced as a check on the will since in the modern rational state the individual's particular interests are ‘harmonized with the universal’ (p. 160). This view not only explains the source of moral obligation. It also offers a richer and more adequate account of autonomy than the Kantian view, in which, Hegel claims, the individual ‘carries his lord in himself, yet at the same time is his own slave’ (p. 145). True autonomy, cleansed of all subjugation, is possible only in the context of a rational state that reconciles the individual and the social. Yet Hegel's concerns about Kantian autonomy deserve more scrutiny than they receive. How, exactly, does self-legislation involve self-enslavement? At best, Hegel's claim that a person with Kantian autonomy ‘is his own slave’ is just as puzzling as Kant's claim that a person can give himself a law. At worst, it is vacuous rhetoric. (Schopenhauer beckons toward one of the exits at this point.) One may also question the worries about ‘dualism’. Kant's account of the relation between practical reason and inclination turns on the difference between higher and lower faculties of desire, not on some rigid dualism between the two. Moreover, he thinks any exercise of the faculty of desire is grounded in the faculty of cognition. This may be an implausibly cognitive or intellectualist view of desire, but that's a different problem.

In the third part of the book, Stern explains Kierkegaard's response to Hegel. According to the standard story, the development of post-Kantian ethics culminates in Kierkegaard's existentialism, which rejects the Hegelian picture in favour of a view that overcomes the paradoxical nature of Kantian autonomy by pushing it to its logical conclusion. Stern quotes MacIntyre's version of the story: ‘for Kierkegaard […] “[t]he individual utters his moral precepts to himself in a far stronger sense than the Kantian individual did; for their only sanction and authority is that he has chosen to utter them” ’ (p. 17). Stern, by contrast, claims that Kierkegaard responds to Hegel by returning to a version of divine command theory. His reading of Fear and Trembling and Either/Or argues that Hegel's social command account of obligation is the prime target. And his reading of Works of Love argues that, according to Kierkegaard, the only way to make sense of the command to love one's neighbour is to understand it as a command from God. No other account of obligation can do justice to its demandingness. Hegel's social theory merely waters it down. The command to love one's neighbour is genuinely radical and shocking. It requires something that is not in our nature, and for this reason we need divine assistance and forgiveness. Stern's reading thus highlights Kierkegaard's connection to earlier debates between natural law theorists and divine command theorists. According to his version of the story, Kierkegaard's response to Hegel returns us to precisely the theological tradition Kant sought to escape. This is not reactionary or retrograde. On the contrary, Kierkegaard confronts us with the very real limits of both Kant's and Hegel's solutions to the problem of moral obligation, and reminds us of the powerful reasons why so many philosophers and theologians have believed that the concept of genuine moral obligation makes no sense without God.

Stern's treatment of Kant is the longest and most satisfying part of the book. Two main features are particularly noteworthy. The first is the claim that Kant is a realist rather than an anti-realist about moral value. A number of important Kant scholars defend realist interpretations. But Stern's account is novel in that it directly confronts the assumption that realism is incompatible with autonomy. Intuitively, one might think that moral realism threatens autonomy. After all, autonomy is self-legislation, and if Kant were a moral realist, he would have to think that in obeying the moral law moral agents obey something other than themselves, something alien to their wills. Stern argues persuasively against this intuition. Moreover, contra Rawls and others, Kant expresses no worries about realism—not even in his famous discussion of the ‘paradox of method’. His disagreement with Pistorius is a disagreement about method, not meta-ethics. Kant claims that starting with a substantive conception of the good, rather than a formal conception of the right, leads to eudaimonism. This is a problem because eudaimonism cannot explain the categorical nature of moral demands, as it grounds moral obligation in the agent's desire for happiness (and his necessarily empirical conception of what happiness amounts to).

The second feature that must be mentioned is Stern's account of Kant's ‘hybrid’ theory of moral obligation. This theory combines features of a number of rival views in order to offer a satisfying solution to the problem of obligation. Kant combines realism and anti-realism by being a realist about the content of morality and an anti-realist about its obligatory force. He combines internalism and externalism by being an externalist about the right and the good and an internalist about obligation and duty. (In this context, Stern makes an illuminating comparison between Kant's position and W.D. Falk's. Both believe that a person can judge an act to be right or good without being motivated to perform it, but he cannot take himself to be obligated or to have a duty without being at least somewhat motivated to perform that duty.) Finally, Kant combines natural law theory and divine command theory by taking the natural law position on the right and the good and the divine command position on obligation and duty. The basic idea at the core of Kant's hybrid theory is that, like Leibniz and Clarke, he believes the difference between right and wrong is explained by the very nature of things. But, like Barbeyrec and Crusius, he does not think the nature of things can by themselves impose obligations. A good theory of obligation will account for the experience of being bound by a principle and the extent to which in being so bound one is genuinely ‘necessitated’ or constrained to act, and no appeal to the nature of things can explain this. Kant tries to explain it by appealing to the difference between a holy will and the corrupt finite wills of human beings. A holy will necessarily decides in accordance with the demands of morality. It cannot experience the latter as a form of constraint because there is no possibility of the holy will deciding to violate those demands. The concepts of moral constraint (Zwang) and necessitation (Nötigung) cannot be meaningfully applied to a holy will. They apply to creatures like us because we must struggle to fulfil the demands of morality, as these frequently run counter to our desires and needs. The demands of morality have obligatory force for us precisely because it is in our nature to resist them, to experience them as obstacles to the pursuit of our interests. One version of this claim says that ‘ought’ implies ‘might not’. Without possibility of failure, there is no obligation. But Stern argues for a stronger version of the claim. The experience of resistance is essential to the existence of obligation (pp. 83–84). He does not explore the implications of this idea as thoroughly as one might like. Does it imply that on Kant's view it is false to say that I am under an obligation to help someone in need if it is true that I am glad to do so? Or that I have no duty to x in cases where I am inclined to do x anyway? Does Kant really think that in such cases a person simply has no obligation? That seems so odd it suggests that Stern ties the existence of obligation too closely to the experience of resistance.

One might also wonder how useful it is to describe Kant's view of moral constraint as anti-realist. The whole point of being an anti-realist about some category of items is to say that talk of such items does not track reality. Being an anti-realist about moral obligation would imply that no claim that a person has a duty to x or is obligated to x could be true—either because all such claims are false or because no such claims can be either true or false. But it is not easy to see why, on Stern's reading, Kant would be committed to this position. Stern's reading seems to imply that if S feels bound to abide by principle P and P correctly tracks the nature of things, then it would be true that S is obligated to follow P and true that S has a duty to do what P says he must do. There are no mind-independent facts about moral obligation or duty on this account. But that is just because facts about obligation depend on facts about feelings of resistance experienced by creatures with non-holy wills. This does not imply that there are no facts about moral obligation. Lots of facts depend on other facts. That does not mean they aren't facts.

In other words, Stern does not do everything in this book. But no book does everything, and it is hard to imagine how one could do more in the space of 250 pages. So let me emphasize that these are minor reservations about an extremely accomplished piece of work. Understanding Moral Obligation presents a powerful challenge to the ‘standard story’ of the period, and it is a delight to read. Fresh insights—about historical figures and contemporary debates—can be found on nearly every page. Anyone interested in the topic or any of the three figures named in its title will profit greatly from studying it carefully.Footnote ¹